A web lamination device of the above described type is disclosed, for example, in Japanese Unexamined Patent Publication (Kokai) No. 4-82953 and No. 4-267149. The conventional device of this type is illustrated in FIG. 9. In FIG. 9, a longitudinal web 1 has longitudinal fibrous elements 10, and a transverse web 2 has transverse fibrous elements 9. The transverse web 2 also has selvages 3 for conveying the web. The longitudinal web 1 and the transverse web 2 are respectively fed to a laminating roll 5 and laminated with each other at the laminating roll 5.
Prior to reaching the laminating roll 5, the transverse fibrous elements 9 of the transverse web 2 are liable to slacken, as shown in FIG. 10, and a width of the transverse web 2 is reduced depending on the slack, as shown in FIG. 11. Accordingly, the transverse web 2 is guided by a pair of cloth guiders 8 or the like arranged directly upstream of the laminating roll 5, to introduce the transverse web 2 to the laminating roll 5 under lateral tension.
On the other hand, as shown in FIG. 9, the longitudinal web 1 having a predetermined width is first introduced to an introduction roll 4 to reverse its course to the laminating roll 5, and is overlaid on the transverse web 2 introduced to the laminating roll 5. Therefore, the transverse web 2 is pressed onto the laminating roll 5 due to the longitudinal tension of the longitudinal web 1. The longitudinal web 1 and/or the transverse web 2 have an adhesive layer on at least one surface thereof to be in contact with the other, which is heated while the laminated webs run around the outer circumference of the laminating roll 5, and the longitudinal web 1 and the transverse web 2 are adhered with each other to form a laminated product 7.
The transverse fibrous elements 9 in the transverse web 2 must be regularly arranged in the transverse direction prior to being overlaid with the longitudinal web 1, as shown in FIG. 11. However, the transverse fibrous elements 9 are liable to skew, as illustrated in FIG. 12. This is because the opposite selvages 3 are not strictly homogeneous to each other. That is, since the selvages 3 contribute to transport the transverse web 2 but the transverse fibrous elements 9 does not contribute to transport the transverse web 2, it is necessary to draw the selvages 3 forward to introduce the transverse web 2 into the laminating roll 5, which causes a significant tension in the selvages 3.
If the cross-sectional area and/or the stretching characteristic of one of the selvages 3, 3 do not strictly coincide with those of the other, there may be a difference in expansion between the selvages. Even if this difference is slight, it accumulates with time, and one of ends of the transverse fibrous elements 9 at which the selvage is easily extensible is delayed, so the transverse fibrous elements 9 are skewed. When the transverse fibrous elements 9 are skewed to a certain extent, the transverse fibrous elements 9 themselves operate to pull the delayed selvage. Thereby the tension load applied to the delayed selvage is reduced and the selvage does not expand furthermore, equilibrium being established so that the web runs while maintaining the transverse fibrous elements in the skewed state.
If the transverse fibrous elements 9 are skewed, the transverse fibrous elements 9 do not naturally intersect the longitudinal fibrous element 10 at a right angle, which does not result in a desired product. Accordingly, it is necessary to avoid skewing of the transverse web, and if skewing occurs, it should be immediately corrected. However, it is difficult to prevent skewing by homogenizing the selvages because there is a possible limit in this homogenization. Accordingly, there is a problem that once skewing occurs, it is necessary to stop and restart the production line, which significantly disturbs productivity.